diff --git a/.gitignore b/.gitignore
index 55cf575..d0d754e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -9,7 +9,8 @@ coverage
 .env.*
 !.env.example
 
-# Local data / caches
+# Local data / caches (matches at any depth — covers
+# deploy/simulation/data/, indexer/data/, etc.)
 data/
 *.log
 .vitest-cache
@@ -26,3 +27,8 @@ docs/img/*.mmd
 # secrets inside their entries that .gitignore can't strip from a zip.
 # Don't republish them.
 docs/*.zip
+
+# Python bytecode (only present under docs/ reference material).
+# .pyc files can embed absolute dev-machine paths via co_filename.
+__pycache__/
+*.pyc
diff --git a/deploy/simulation/README.md b/deploy/simulation/README.md
new file mode 100644
index 0000000..2f63e66
--- /dev/null
+++ b/deploy/simulation/README.md
@@ -0,0 +1,152 @@
+# `apex-simulation` host runbook
+
+A second deploy target dedicated to "simulation"-style supplier capabilities
+(starting with CPU-only PiperTTS as `audio.synthesize.v1`). Independent of
+`apex-dashboard` so heavy local models can come and go without affecting
+the marketplace's chain-follower / buyer-app.
+
+## Layout
+
+```
+deploy/simulation/
+├── docker-compose.traefik.yml      # Standalone Traefik on :80
+├── docker-compose.tts-piper.yml    # PiperTTS behind OpenAI-compat shim
+├── deploy.sh                       # rsync from laptop → apex-simulation, compose up
+└── data/                           # bind-mount target (created on host; gitignored)
+    └── tts-piper/{voices,config}/  # downloaded Piper voices persist here
+```
+
+## Prereqs
+
+**On the laptop**: SSH alias `apex-simulation` resolving to the new host
+(see `~/.ssh/config`). `rsync` available locally.
+
+**On `apex-simulation` (one-shot)**:
+
+```sh
+# As root (or via sudo) — create the deploy user:
+adduser --disabled-password --gecos "" deploy
+usermod -aG docker deploy
+sudo -u deploy mkdir -m 700 /home/deploy/.ssh
+# Paste your laptop's public key:
+sudo -u deploy tee /home/deploy/.ssh/authorized_keys >/dev/null <<'EOF'
+ssh-ed25519 AAAA…  your-laptop-key
+EOF
+sudo -u deploy chmod 600 /home/deploy/.ssh/authorized_keys
+
+# Optional but recommended — disable password SSH:
+sed -i 's/^#\?PasswordAuthentication.*/PasswordAuthentication no/' /etc/ssh/sshd_config
+systemctl reload sshd
+```
+
+## Cloudflare DNS
+
+Add an A record `tts-piper.vector.testnet.apexfusion.org` → apex-simulation
+public IP. Orange cloud (proxied) is fine — CF terminates TLS, forwards
+HTTP to Traefik on :80.
+
+If CF later flags the path with a 502, mirror the existing
+`Skip mp-buyers on testnet` rule for `tts-piper.…` (see
+`deploy/CLOUDFLARE_WAF_BYPASS.md`). TTS bodies are short text so this is
+unlikely, but the runbook is there if needed.
+
+## Deploy
+
+From the laptop, repo root:
+
+```sh
+# First time (and every subsequent change):
+bash deploy/simulation/deploy.sh
+```
+
+`deploy.sh` does:
+
+1. `mkdir -p` the bind-mount target dirs on the remote.
+2. `rsync` only `deploy/simulation/*` to `/home/deploy/marketplace-simulation/deploy/simulation/` on apex-simulation. The voices dir (`data/`) is excluded — Piper downloads voices on first run.
+3. `docker network create traefik-net` (idempotent).
+4. `docker compose ... up -d` for Traefik then TTS.
+5. Print container status + last 20 lines of TTS logs.
+
+Selective re-deploys:
+
+```sh
+bash deploy/simulation/deploy.sh --traefik-only
+bash deploy/simulation/deploy.sh --tts-only
+```
+
+## Voice quality
+
+The compose file defaults to `PRELOAD_MODEL=en_US-lessac-high` — Piper's
+highest-quality American-English single-speaker voice (~60 MB). Other
+top-tier options:
+
+| Model | Description | Size |
+|---|---|---|
+| `en_US-lessac-high` | Female, very natural, default | 60 MB |
+| `en_GB-alan-high` | British male | 65 MB |
+| `en_US-ryan-high` | American male | 60 MB |
+| `en_US-libritts_r-medium` | Multi-speaker (904 voices) | 75 MB |
+
+Browse the rest at <https://huggingface.co/rhasspy/piper-voices/tree/main>.
+To switch, edit `PRELOAD_MODEL` in `docker-compose.tts-piper.yml`, then:
+
+```sh
+bash deploy/simulation/deploy.sh --tts-only
+```
+
+## Verify TTS end-to-end
+
+From any laptop that resolves the CF hostname:
+
+```sh
+curl -s -X POST https://tts-piper.vector.testnet.apexfusion.org/v1/audio/speech \
+  -H "Content-Type: application/json" \
+  -d '{
+    "model": "tts-1-hd",
+    "input": "Hello from the local agents marketplace. PiperTTS, served via openedai-speech, signed via the future bonded escrow.",
+    "voice": "alloy",
+    "response_format": "wav"
+  }' \
+  -o /tmp/out.wav
+
+aplay /tmp/out.wav     # or `mpv /tmp/out.wav` / `paplay /tmp/out.wav`
+```
+
+The OpenAI shim maps the six standard voice names (`alloy`, `echo`, `fable`,
+`onyx`, `nova`, `shimmer`) onto the bundled Piper voices. The `model`
+field is informational — Piper has no model picker beyond voice.
+
+## Health probes
+
+```sh
+# Traefik (returns 404 with no host = alive)
+curl -i http://<server-ip>:80
+
+# TTS service via Traefik
+curl -s https://tts-piper.vector.testnet.apexfusion.org/v1/models | jq .
+```
+
+## Wiring as a marketplace supplier (later)
+
+Once the audio is sound, this becomes a second supplier deployment:
+
+1. Add a `marketplace-supplier-tts` compose on apex-simulation (clone of
+   `deploy/testnet/docker-compose.supplier.yml`, swap `OLLAMA_URL` →
+   `http://marketplace-tts-piper:8000`, advertise capability
+   `audio.synthesize.v1`).
+2. New wallet (`SUPPLIER_PRIV_KEY_HEX`) so the bond is independent of
+   the chat supplier.
+3. `pnpm tx:post-advert` against this host's wallet to publish the
+   capability. The buyer Dashboard then sees two suppliers — one for
+   `llm.text.generate.v1`, one for `audio.synthesize.v1`.
+
+Out of scope here — file under a future `UX-supplier-tts` task.
+
+## Troubleshooting
+
+| Symptom | Likely cause | Fix |
+|---|---|---|
+| `404` on the CF hostname | Traefik up but no router matches | Container labels missed; `bash deploy.sh --tts-only` |
+| `502` on first call | Cold start downloading the Piper voice (30–90 s) | Wait & retry, or pre-warm with a short curl |
+| Audio file is 0 bytes | Voice model failed to download (no outbound network from host?) | `ssh apex-simulation 'docker logs marketplace-tts-piper'` — look for huggingface fetch errors |
+| Want a different voice | Change `PRELOAD_MODEL` in `docker-compose.tts-piper.yml` | `bash deploy/simulation/deploy.sh --tts-only` |
diff --git a/deploy/simulation/deploy.sh b/deploy/simulation/deploy.sh
new file mode 100755
index 0000000..bee3461
--- /dev/null
+++ b/deploy/simulation/deploy.sh
@@ -0,0 +1,91 @@
+#!/usr/bin/env bash
+# deploy/simulation/deploy.sh — push the simulation-host stack to apex-simulation.
+#
+# Mirrors the rsync-only pattern used for apex-dashboard (no git clone on
+# the remote — only the files we need actually leave the laptop). Idempotent:
+# safe to re-run after editing either compose file.
+#
+# Usage:
+#   bash deploy/simulation/deploy.sh                  # rsync + compose up
+#   bash deploy/simulation/deploy.sh --traefik-only   # rsync + (re)start Traefik
+#   bash deploy/simulation/deploy.sh --tts-only       # rsync + (re)start TTS
+#
+# Prereqs on local laptop:
+#   - SSH alias `apex-simulation` resolves (see ~/.ssh/config)
+#
+# Prereqs on remote:
+#   - Docker engine + compose plugin
+#   - User `deploy` exists, in `docker` group
+#   - Run once: `ssh apex-simulation 'docker network create traefik-net'`
+
+set -euo pipefail
+
+REMOTE_HOST="${REMOTE_HOST:-apex-simulation}"
+REMOTE_DIR="${REMOTE_DIR:-/home/deploy/marketplace-simulation}"
+
+cd "$(dirname "$0")/../.."   # repo root
+
+WHAT="${1:-all}"
+case "$WHAT" in
+  --traefik-only) WHAT=traefik ;;
+  --tts-only)     WHAT=tts ;;
+  ""|all|--all)   WHAT=all ;;
+  *) echo "unknown arg: $WHAT" >&2; exit 1 ;;
+esac
+
+echo "→ rsync deploy/simulation/ → $REMOTE_HOST:$REMOTE_DIR/deploy/simulation/"
+ssh "$REMOTE_HOST" "mkdir -p $REMOTE_DIR/deploy/simulation/data/tts-piper/voices $REMOTE_DIR/deploy/simulation/data/tts-piper/config"
+
+# Only the files we need on the host. Excludes data/ so we don't ship the
+# voice models from the laptop (they're downloaded on the host on first run).
+rsync -avz --delete \
+  --exclude='data/' \
+  --exclude='*.bak' \
+  deploy/simulation/ \
+  "$REMOTE_HOST:$REMOTE_DIR/deploy/simulation/"
+
+echo
+echo "→ ensure traefik-net exists on remote"
+ssh "$REMOTE_HOST" "docker network inspect traefik-net >/dev/null 2>&1 || docker network create traefik-net"
+
+if [ "$WHAT" = "all" ] || [ "$WHAT" = "traefik" ]; then
+  echo
+  echo "→ traefik up"
+  ssh "$REMOTE_HOST" "cd $REMOTE_DIR && docker compose -f deploy/simulation/docker-compose.traefik.yml up -d"
+fi
+
+if [ "$WHAT" = "all" ] || [ "$WHAT" = "tts" ]; then
+  echo
+  echo "→ tts-piper up (force-recreate so env / image changes take effect)"
+  ssh "$REMOTE_HOST" "cd $REMOTE_DIR && docker compose -f deploy/simulation/docker-compose.tts-piper.yml up -d --force-recreate"
+
+  # Wait for the container to become healthy before applying voice extras.
+  # On a fresh host the bind-mount config dir is empty until openedai-speech-min
+  # populates it, which only happens after the server starts answering /v1/models.
+  # If we touch /app/config/voice_to_speaker.yaml before then, the file isn't
+  # there yet. The healthcheck (`curl /v1/models`) gates that for us.
+  echo
+  echo "→ waiting for tts-piper to become healthy (start_period up to 90s)"
+  ssh "$REMOTE_HOST" "until [ \"\$(docker inspect marketplace-tts-piper --format '{{.State.Health.Status}}')\" = healthy ]; do sleep 5; done"
+
+  # Install extra voices (e.g. en_US-lessac-high) and the yaml aliases for
+  # them. Idempotent — does nothing on subsequent runs once everything is
+  # in place. Restarts the container only if it actually changed something.
+  echo
+  echo "→ apply voice extras (idempotent; restarts container if it changed anything)"
+  ssh "$REMOTE_HOST" "cd $REMOTE_DIR && bash deploy/simulation/install-voice-extras.sh"
+fi
+
+echo
+echo "→ container status"
+ssh "$REMOTE_HOST" "docker ps --filter name=traefik --filter name=marketplace-tts-piper --format 'table {{.Names}}\t{{.Status}}\t{{.Ports}}'"
+echo
+echo "→ tail tts-piper logs (first 20 lines)"
+ssh "$REMOTE_HOST" "docker logs --tail 20 marketplace-tts-piper 2>&1 || true"
+
+echo
+echo "Done. Test from your laptop once CF DNS is set:"
+echo "  curl -s -X POST https://tts-piper.vector.testnet.apexfusion.org/v1/audio/speech \\"
+echo "    -H 'Content-Type: application/json' \\"
+echo "    -d '{\"model\":\"tts-1\",\"input\":\"Hello.\",\"voice\":\"alloy\",\"response_format\":\"wav\"}' \\"
+echo "    -o /tmp/out.wav && aplay /tmp/out.wav"
diff --git a/deploy/simulation/docker-compose.traefik.yml b/deploy/simulation/docker-compose.traefik.yml
new file mode 100644
index 0000000..fa1e642
--- /dev/null
+++ b/deploy/simulation/docker-compose.traefik.yml
@@ -0,0 +1,69 @@
+# deploy/simulation/docker-compose.traefik.yml — apex-simulation Traefik
+#
+# Runs as its own compose project so individual services (TTS today,
+# more later) can be brought up/down independently without touching the
+# reverse proxy. Cloudflare terminates TLS in front, so we expose a
+# single :80 entrypoint and rely on CF Full / Flexible SSL for the
+# browser-side connection (same pattern as the apex-dashboard host).
+#
+# Bring up:
+#   docker compose -f deploy/simulation/docker-compose.traefik.yml up -d
+#
+# Verify:
+#   curl -i http://<server-ip>:80    # 404 from Traefik = healthy / no router matched
+
+name: traefik
+
+services:
+  traefik:
+    # `:latest` (currently v3.5+) carries an updated Docker SDK that
+    # negotiates correctly against Docker daemon 29.x. v3.1 — and even
+    # v3.4 with `DOCKER_API_VERSION=1.45` — still requested API 1.24,
+    # which Docker 29 rejects ("Minimum supported API version is 1.40").
+    # Result: provider error loop, no routers ever published.
+    image: traefik:latest
+    container_name: traefik
+    restart: unless-stopped
+    command:
+      # Docker provider — services join `traefik-net` and add labels.
+      - --providers.docker=true
+      - --providers.docker.exposedbydefault=false
+      - --providers.docker.network=traefik-net
+      # Single HTTP entrypoint (Cloudflare does TLS in front).
+      - --entrypoints.web.address=:80
+      # Health probe + access logs.
+      - --ping=true
+      # API (insecure) so we can introspect routers/services on :8080
+      # via `docker exec traefik wget -qO- http://localhost:8080/api/...`.
+      # Not published on the host, so only reachable from inside the
+      # traefik-net or via docker exec.
+      - --api=true
+      - --api.insecure=true
+      - --log.level=DEBUG
+      - --log.format=json
+      - --accesslog=true
+      - --accesslog.format=json
+    ports:
+      - "80:80"
+    volumes:
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+    networks:
+      - traefik-net
+    healthcheck:
+      test: ["CMD", "traefik", "healthcheck", "--ping"]
+      interval: 30s
+      timeout: 3s
+      retries: 3
+    logging:
+      driver: json-file
+      options:
+        max-size: "20m"
+        max-file: "3"
+
+networks:
+  # traefik-net is created once out-of-band (`deploy.sh` does
+  # `docker network create traefik-net`) so the TTS compose project
+  # can also attach to it. Both compose projects mark it `external`.
+  traefik-net:
+    external: true
+    name: traefik-net
diff --git a/deploy/simulation/docker-compose.tts-piper.yml b/deploy/simulation/docker-compose.tts-piper.yml
new file mode 100644
index 0000000..e2f45b7
--- /dev/null
+++ b/deploy/simulation/docker-compose.tts-piper.yml
@@ -0,0 +1,80 @@
+# deploy/simulation/docker-compose.tts-piper.yml — PiperTTS as OpenAI-compatible /v1/audio/speech
+#
+# Wraps rhasspy/piper (CPU neural TTS) behind matatonic/openedai-speech,
+# which exposes the OpenAI Audio API (`POST /v1/audio/speech`). Once
+# online behind Traefik on `apex-simulation`, this becomes a viable
+# capability for a future `audio.synthesize.v1` supplier in the
+# marketplace — same OpenAI-shaped HTTP surface as Ollama for chat.
+#
+# `*-min` image is the CPU/Piper-only variant (the full image pulls
+# parler-tts + xtts which want a GPU). Default model is `en_US-amy-low`
+# — small (~10 MB) and fast on CPU. Add `PRELOAD_MODEL=...` env to
+# pre-warm a different voice on boot.
+#
+# Bring up:
+#   docker compose -f deploy/simulation/docker-compose.tts-piper.yml up -d
+#
+# Quick test (from any host that resolves the Traefik route):
+#   curl -s -X POST https://tts-piper.vector.testnet.apexfusion.org/v1/audio/speech \
+#     -H "Content-Type: application/json" \
+#     -d '{"model":"tts-1","input":"Hello from the marketplace.","voice":"alloy","response_format":"wav"}' \
+#     -o /tmp/out.wav && aplay /tmp/out.wav   # or `mpv` / `ffplay`
+
+name: marketplace-tts-piper
+
+services:
+  tts-piper:
+    image: ghcr.io/matatonic/openedai-speech-min:latest
+    container_name: marketplace-tts-piper
+    restart: unless-stopped
+    environment:
+      # Pre-load Piper's highest-quality American-English voice so first
+      # /v1/audio/speech doesn't pay the model-download tax. `-high`
+      # variants are 60–70 MB and noticeably more natural than `-low`/
+      # `-medium` on CPU. Browse alternatives at
+      # https://huggingface.co/rhasspy/piper-voices/tree/main
+      #   en_US-lessac-high       — clean female, very natural (default)
+      #   en_GB-alan-high         — British male
+      #   en_US-ryan-high         — American male
+      #   en_US-libritts_r-medium — multi-speaker (904 voices)
+      PRELOAD_MODEL: en_US-lessac-high
+      # Expose port — matches the loadbalancer label below.
+      PORT: "8000"
+    volumes:
+      # Host bind mounts (not Docker named volumes) so the deploy user can
+      # `ls`/`du`/back-up the downloaded Piper voices directly without
+      # `docker volume inspect`. Paths are relative to THIS compose file,
+      # i.e. `deploy/simulation/data/tts-piper/{voices,config}` from the
+      # repo root. Create the dirs once before `compose up` (see README).
+      - ./data/tts-piper/voices:/app/voices
+      - ./data/tts-piper/config:/app/config
+    healthcheck:
+      # /v1/models is the OpenAI-shape model list; a 200 here proves the
+      # server is up and at least one voice is loaded. Image ships with
+      # curl (and python3) but NOT wget — using wget here marks the
+      # container unhealthy on every probe, and Traefik then filters it
+      # out of the docker provider ("Filtering unhealthy or starting
+      # container"), which means no router ever registers.
+      test: ["CMD-SHELL", "curl -fsS http://localhost:8000/v1/models >/dev/null || exit 1"]
+      interval: 30s
+      timeout: 5s
+      retries: 3
+      start_period: 90s
+    networks:
+      - traefik-net
+    labels:
+      - "traefik.enable=true"
+      - "traefik.docker.network=traefik-net"
+      - "traefik.http.routers.tts-piper.entrypoints=web"
+      - "traefik.http.routers.tts-piper.rule=Host(`tts-piper.vector.testnet.apexfusion.org`)"
+      - "traefik.http.services.tts-piper.loadbalancer.server.port=8000"
+    logging:
+      driver: json-file
+      options:
+        max-size: "10m"
+        max-file: "3"
+
+networks:
+  traefik-net:
+    external: true
+    name: traefik-net
diff --git a/deploy/simulation/install-voice-extras.sh b/deploy/simulation/install-voice-extras.sh
new file mode 100755
index 0000000..20b6cab
--- /dev/null
+++ b/deploy/simulation/install-voice-extras.sh
@@ -0,0 +1,72 @@
+#!/usr/bin/env bash
+# install-voice-extras.sh — runs ON THE HOST after `docker compose up`
+# for marketplace-tts-piper to install Piper voices and yaml mappings
+# beyond what the openedai-speech-min image ships with.
+#
+# Idempotent: every step is a no-op if it already finished previously.
+# Safe to re-run after a host wipe — `deploy.sh` invokes it at the end
+# of every tts deploy so a fresh `data/` dir gets the same voices back.
+#
+# What it does (in order):
+#   1. Ensure the bind-mount voice files are present (curl -sSL with `[ -s ]` guard).
+#      Voice files are large (~100 MB) and gitignored under `data/`, so they
+#      have to be (re)downloaded onto each fresh host.
+#   2. Copy voice-mappings.py into the container and execute it as root.
+#      The script edits /app/config/voice_to_speaker.yaml (which is a host
+#      bind-mount) to add custom voice aliases. It prints "modified" or
+#      "unchanged" — we restart only on the former.
+#   3. Restart the container if either step (1) or (2) changed something,
+#      so Piper picks up the new files / yaml.
+#
+# Usage:
+#   bash deploy/simulation/install-voice-extras.sh
+
+set -euo pipefail
+
+SIM_DIR="$(cd "$(dirname "$0")" && pwd)"
+VOICES_DIR="$SIM_DIR/data/tts-piper/voices"
+CONTAINER="marketplace-tts-piper"
+
+mkdir -p "$VOICES_DIR"
+changes=0
+
+# --- 1. Voice files to install (filename → URL) ---
+# Add entries here when you want another voice baked into the deploy.
+# Each .onnx pairs with a .onnx.json — both must be downloaded.
+voices=(
+  "en_US-lessac-high.onnx|https://huggingface.co/rhasspy/piper-voices/resolve/main/en/en_US/lessac/high/en_US-lessac-high.onnx"
+  "en_US-lessac-high.onnx.json|https://huggingface.co/rhasspy/piper-voices/resolve/main/en/en_US/lessac/high/en_US-lessac-high.onnx.json"
+)
+
+for entry in "${voices[@]}"; do
+  fn="${entry%%|*}"
+  url="${entry##*|}"
+  if [ -s "$VOICES_DIR/$fn" ]; then
+    echo "voice: already installed — $fn"
+    continue
+  fi
+  echo "voice: downloading $fn"
+  # `--fail` so HTTP 4xx/5xx aborts (HF returns html on 404 by default).
+  # Download to a tmp file then mv, so a partial download from a network
+  # blip doesn't leave a half-file that the next run treats as installed.
+  tmp="$VOICES_DIR/.${fn}.partial"
+  curl -sSL --fail --output "$tmp" "$url"
+  mv "$tmp" "$VOICES_DIR/$fn"
+  changes=1
+done
+
+# --- 2. Yaml mapping additions inside the container ---
+docker cp "$SIM_DIR/voice-mappings.py" "$CONTAINER:/tmp/voice-mappings.py" >/dev/null
+mapping_output="$(docker exec "$CONTAINER" python3 /tmp/voice-mappings.py)"
+echo "mapping: $mapping_output"
+if [[ "$mapping_output" == modified* ]]; then
+  changes=1
+fi
+
+# --- 3. Restart only if anything changed ---
+if [ "$changes" -eq 1 ]; then
+  echo "→ restarting $CONTAINER to pick up new voices/mappings"
+  docker restart "$CONTAINER" >/dev/null
+else
+  echo "✓ voice extras already up to date — no restart needed"
+fi
diff --git a/deploy/simulation/voice-mappings.py b/deploy/simulation/voice-mappings.py
new file mode 100644
index 0000000..0c5d701
--- /dev/null
+++ b/deploy/simulation/voice-mappings.py
@@ -0,0 +1,60 @@
+#!/usr/bin/env python3
+# voice-mappings.py — idempotently apply project-specific voice aliases to
+# /app/config/voice_to_speaker.yaml inside the marketplace-tts-piper container.
+#
+# Why this exists:
+#   The openedai-speech-min image populates voice_to_speaker.yaml on first
+#   start with its OWN defaults (alloy/echo/fable/onyx/nova/shimmer mapped
+#   onto the bundled LibriTTS + northern-english-male voices). Voices we
+#   install ourselves (e.g. en_US-lessac-high) need a name in that yaml so
+#   the OpenAI-shape `voice` field can resolve to them. This script adds
+#   those entries — and only those — without disturbing the defaults.
+#
+# Idempotency contract:
+#   Reads the yaml, compares each desired entry against what's there, only
+#   rewrites if at least one entry is missing or stale. Prints "modified"
+#   on write, "unchanged" otherwise — install-voice-extras.sh greps for
+#   "modified" to decide whether to restart the container.
+#
+# Run via:
+#   docker cp voice-mappings.py marketplace-tts-piper:/tmp/voice-mappings.py
+#   docker exec marketplace-tts-piper python3 /tmp/voice-mappings.py
+
+import sys
+import yaml
+
+CONFIG_PATH = "/app/config/voice_to_speaker.yaml"
+
+# Mappings to ensure exist under `tts-1`. Adding more voices later is a
+# matter of dropping the .onnx + .onnx.json into voices/ (handled by
+# install-voice-extras.sh) and adding an entry here.
+DESIRED_TTS1 = {
+    # en_US-lessac-high — high-quality American female single-speaker voice.
+    # Single-speaker model, so no `speaker:` key.
+    "lessac": {"model": "voices/en_US-lessac-high.onnx"},
+}
+
+
+def main() -> int:
+    with open(CONFIG_PATH) as f:
+        cfg = yaml.safe_load(f) or {}
+
+    cfg.setdefault("tts-1", {})
+
+    modified_keys = []
+    for name, mapping in DESIRED_TTS1.items():
+        if cfg["tts-1"].get(name) != mapping:
+            cfg["tts-1"][name] = mapping
+            modified_keys.append(name)
+
+    if modified_keys:
+        with open(CONFIG_PATH, "w") as f:
+            yaml.safe_dump(cfg, f, sort_keys=False)
+        print(f"modified — applied: {', '.join(modified_keys)}")
+    else:
+        print("unchanged — all mappings already present")
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())